Centrifugal molding machine



Dec. 11, 1934. 1 F NE PAGE 1,984,197

CENTRIFUGAL MOLDTNG MACHINE Filed Aug. 2l, 1931 A. I W INVENTOR PatentedDec. 11, 1934 CENTRIFUGAL MOLDING MACHINE Justus F. Ne Page, Seattle,Wash., assigner to Ne Page McKenny Co., Seattle, Wash., a corporation ofWashington Application August 21', 1931, Serial No. 558,529

11 Claims.

My invention relates to improvements in centrifugal molding machines.particularly for the manufacture of long reinforcedconcrete articlesvand to the method of manufacturing the same, with specialreference tothe production of ornamental, reinforced concrete, street lightingstandards having relatively large -diameter base portions and smalldiameter tapering shaft portions, and isl inthe nature of an improvementon my U. S. Patent No. 1,777,763 assigned to Ne Page McKenny Co.

The object of my invention is to provide improved means for increasingthe rate of production and decreasing the cost of molding concretearticles.

A further object is to provide improved means for the manufacture ofconcrete articles from a high water-cement ratio fiuid mix whereby thesame is'changed into uniformly low Water-cement ratio, high strengthconcrete during the process Aof manufacture.

Another object is to provide improved means whereby long, ornamentalconcrete articles, uniformly free from interior and surface defects, maybe cast from a uid concrete mix.

A final object is to providean improved method of manufacturinghigh-strength concrete articles from a liuid concrete mix.

With the above and related objects in view, thev posed mold partly insection. 4

Fig. 2 is a plan View of the spinning and vibrating mechanism with themold, spinning table, load rollers and gear box cover removed.

Fig. 3 is a sectional elevation of thespinning and vibrating mechanism,on broken line A-A of jig. 2, in operative combination with an elevationbroken line B-B to a larger scale, showing one of the adjustablewheelsmounted on the eccentric portion of the shaft.

Like numerals of reference indicate correspond'- ing parts in thedifferent figures of the drawing.

(Cl. .Z5-30) The machine of my invention in its preferred form consistsof a combination spinning and vibrating unit 1, an upright mold unit 2removably mounted thereon, and a removable topconnection assembly 3supported by a suitable tower structure, not shown, arranged to expeditethe filling of the mold with fluid concrete.

The combination spinning and vibrating unit is assembled upon a mainframe casting 4 providing a tapered circular track portion 5 and a baseplate portion adapted to bear upon a suitable concrete foundation 7, towhich the frame is secured by means of anchor bolts 8. A cover 9,removably secured to frame 4, provides an oil tight compartment whichencloses a bevel gear speed reducer, the bevel gear Wheel l0 of which isxedly secured to a vertical shaft 11, rotatively mounted in step bearingl2, thrust bearing 13 and guide bearing 14 as shown clearly in Fig. 3 ofthe drawing. The pinion 15 of the speed reducer is xedly secured to ahorizontally disposed shaft 16 rotatively mounted in bearing 17 providedin the frame casting. 'Ihe projecting end of shaft 16 may be directly.connected by means of a coupling 18 to a variable-speed electric motor19 mounted on an extension of base plate 6.

A spinning table 20, having a beveled circular track portion 21 and hub22, is revolvably supported by a plurality of tapered rollers 23 adaptedto traverse said base track 5 and said table track 2l. Spinning table 20is rotated and maintained in alignment by the upwardly projectingcasehardened end of shaft 11, Which is squared as at 24 to form aslidable driving connection with hub 22 through the intermediacy of ahardened steel bushing 25, which is xedly secured in said hub andprovided with a square aperture to receive said squared portion 24 ofshaft 11.

Tapered rollers l23 preferably are composed ot' a resilient materialsuch as vulcanized rubber, similar to that used for automobile fires,which may be molded aroundv bronze sleeve centers 23j.. rIfhisconstruction permits the mold to be vibrated at relatively highfrequency and through the maximum amplitude required Without undueshock'to the moldor other parts of the equipment.

These support rollersare maintained in equiv distant positions aroundtheir circular tracks by means of a split, or two part, spider havinghub ring portions 25 and appended arms 26, which may terminate injournal projections 27 on which rollers 23 are rotatably mounted andSecured in position by nuts 28 and keyed washers 29 abutting 1 suitablevshoulders on said'journals. Arms 26 are strengthened by annular rimhalves 30. Both the hub ring and annular rim halves are connected bybolts (not shown) so the spider may be removed fromthe grooved portion31 of spinning table hub 22, on which it is revolvably mounted. Thisconstruction maintains rollers 23 in proper relation to the taperedtracks and provides accessible means for their inspection andreplacement.

Two wcrm and gear units 32 and 34, each provided with projecting shafts35 having eccentric portions 36, are removably mounted on suitableextensions of base plate 6 with the rotational axes of shafts 35 inalignment and diametrically opposite shaft 11. Wheels 37, having taperedperipheries to conform to the taper of circular track 5, are rotatablymounted on the eccentric portions 36 of shafts 35, the inner ends ofwhich are rotatively supported in suitable bearings in frame casting 4.Shafts 35 are flxedly secured to the worm wheels of gear units 32 and 34which provide the other necessary bearing supports.

Suitable apertures 3S are provided in circular track 5 to allow wheels37 to protrude varying distances above the surface of the track as theeccentric portions 36 are raised by the rotation of' shafts 35, on whichthe worm wheels of said'gear units are mounted in operative combinationwith the worm pinions thereof mounted on shafts. 39.

Power for this operation is supplied by a suitable electric motor 40adapted to drive pinion 41 in gear box 42 through the intermediacy ofcoupling 43. Said pinion in turn drives gear 44 secured to shaft 45journaled in bearings 46 of frame 4. Bevel gears 47 are so positionedand secured to shaft 45 that they drive bevel gears 48 on shafts 39 inopposite directions, and therefore turn shafts 35 in opposite directionsat reduced speed through the intermediacy of worm and gear units 32 and34.

When the eccentric portions 36 of shafts 35 are in their verticallydownward positions, wheels 37, preferably provided with bronze bearingsleeves 37', are withdrawn slightly below the surface of track 5 asshown in Fig. 3. Upon energizing motor 40, it is apparent thateccentrics 36 and Wheels 37 will be moved upwardly through arcs, theradii of which are equal to the distance between the center of shafts 35and the center 0f eccentric portions 36. By using identical worm andgear units, the arcs traversed by wheels 37 will be on the oppositesides of shafts 35, hence diametrically opposite rollers 23 approachingapertures 38 will engage wheels 37 at the same instant for their variousraised positions, and will roll over corresponding protruding portionsof said wheels, thereby coacting to impart a vertical vibration tospinning table 20 and mold unit 2.

The frequency per minute of this vibration is equal to one half therevolutions per minute of the spinning table times the numberl ofsupport rollers employed. The nominal amplitude of the vibration isequal to the radial distance wheels 37 protrude above track 5. Thereforethe fre'- quency of vibration may be varied by the `operator by varyingthe speed of drive motor 19, and the' Patent No. 1,831,128, issued Nov.10, 1931 on application Serial No. 362,622, flled May 13, 1929, lay besupported by gear box 42 and connected by means of gears 50 and 51 toshaft 45, the arrangement being such that when the'operator controlswitches (not shown) are closed to operate motor 40 to raise wheels 37,said motor will be stopped automatically after completing the necessarynumber of revolutions required to raise wheels 37 to their maximumheight. Likewise when the operator switches are closed to reverse motor40 to lower wheels 37. the motor will be stopped automatically aftercompleting the number of revolutions required Vto lower wheels 37 totheir lowest position. Intermediate positions are secured by theoperator by manual operation of the control switches.

Spinning table 20 is provided with a plurality of bosses 52 in whichtorque pins 53 are fixedly mounted. The lower shank portion of a flangedpivot block 54 is adapted to llt tightly in the square aperture ofbushing 25 so that the flange portion bears directly on the hub of thespinning table. Block 54 provides a suitable socket to receive a largepivot ball 64, as shown clearly in Fig. 3. Ball 64 may be composed of aresilient material.

The vertical mold unit 2 is composed of a plurality of flangedlongitudinal sections 55 and a base section 56, which are held inoperative combination by means of bolts 57 passing through the flanges.The mold sections may be assembled around longitudinal reinforcing rods58 and spiral 59, which preferably are secured at their points ofcontact by welding to form a reinforcing cage. This cage is positionedcentrally within the mold by means of welded cross-bar spacers 6l, whichmay serve also to position a conduit pipe 62, preferably closed at itsends .by means of suitable plugs 63 that are readily removable after themold is filled and the concrete has set.

The assembled mold is mounted for axial rotation on spinning table 20through the inter- -mediacy of block 54 and pivot ball 64, which nts ina suitable socket in heavy hub 65 of mold base section 56. Loose fittingapertures'are provided in the annular flange at the base of the mold toreceive torque pins 53, thereby providing a positive yet flexibledriving connection between the spinning table and mold. This method ofmounting assures satisfactory operation of the apparatus even when thereis considerable variation in the vertical alignment of the axis of shaft11 f with the axis of the mold.

The removable top assembly 3 consists of several parts which coact toposition the mold in an upright position on the spinning table so it maybe rotated and vibrated thereby, and facilitates the work of theoperatorin mounting, lling and removing the mold. Referring particularlyto these parts, a. tubular top journal 66, having a flange 67, issecured to the flanged top of the assembled mold by means of bolts 68,and is rotatively mounted in bearing 69 supported by cross members 70removably secured to the tower structure, not shown, which also supportsa platform 7l for the convenience of the operator.

Tubular journal 66 is made of sufficient length to project through aloose-fitting cylindrical aperture provided in the bottom of dischargebasin 72 removably supported by cross members 70, and provided with aspout 73 connecting with a trough 74 which in turn connects with asuitable waste pipe, not shown. A horizontally disposed, internallythreaded, annular disc 75 is screwed onto the threaded top of journal 66after the discharge basin is placed in position. A trough 76, having afunnel-like end 77 and suitably supported as at 78, is used tofacilitate pouring the fluid concrete into the rotating mold.

This construction permits the use of molds of various lengths andshapes. The one here shown for simplicity has been made of circularcross section, but the mechanism and process may be used for molding awide variety of articles by merely substituting other properlyconstructed mold.

When a spiral reinforcing element is employed, the rotation of the moldshould be opposite to the direction traced in following down theconvolutions of the spiral, as this has been found to assist in theelimination .of voids by tending to force the concrete downward as it ispoured into the mold. Whena series of horizontal rings are used in theconstruction of the reinforcing cage, the mold may be rotated in eitherdirection.

In carrying out the process of manufacture with the mold illustrated,the apparatus is assembled as shown in Fig. l, motor 19 is energized andthe mold brought up to the speed required to produce the centrifugingaction and frequency of vibration desired while filling the lower,largef diameter, sectional portion of the mold. Fluid concrete, normallyhaving a high water-cement ratio, may then be poured into the mold,preferably in a small rapidly flowing stream, and motor 40 energized toraise wheels 37 sufficiently to vibrate the mold through the desiredamplitude. These vibrations prevent the inowing concrete from chokingthe mold above the fill, pack the concrete quickly and firmly at thecenter of the ll, and tend to flatten the paraboloidal basin formed atthe top of the ll.

When the mold is rotated without vibration, the surface of the heavyparticles constituting the fill assumes the shape of a paraboloidalbasin due to the combined action of the centrifugal and gravitationalforces, which are indicated by the letters C and G respectively in theforce diagrams of Fig. 4, at various points along curve 8l. This curverepresents the surface of the fill as seen by taking a vertical sectionthrough a diameter ofthe mold. Forces'C and G combine to form aresultant which is normal to the tangent T of the curve at any-givenpoint. The gravitational force G obviously is constant, but thecentrifugal force C varies directly as the square of the distance fromthe center, for a given speed of rotation.

When the mold is vibrated by forcing rollers 23 to roll over theprotruding portion of wheels 37 ink traversing track 5, the mold issuddenly moved upward at a rate gradually diminishing to zero, therebyusing the inertia of the ll to pack the same downward in the mold.Likewise when the mold is stopped suddenly while moving downward at arate gradually increasing from the aforesaid zero the momentum of thefill is used to again pack the same downward in the mold.

As these impulses are rapidly recurring and the.

ll is a plastic, cohesive and ponderous mass, the effect on the fill isthe same as though another force V was added to forces C and G. As forceV is in the same direction as force G, it is evident .that they combineto increase the value and change the direction of the resultant R, asindicated for the point 80 of Fig. 4. Point:80 is the same radialdistance from the center of rotation as point 79 and therefore has thesame value of C, butv due to the change in the direction of R the curve82 representing the surface of the basin is fiattened as compared withcurve 81, which repre- -sents said surface without the vibration. It is3 therefore permissible for a given shape of basin to use higher, speedsof rotation when the mold is vibrated.- This in turn reduces the timere-v quired to squeeze the excess water and air from the fill into thebasin, in which they are carried upward in the mold in the form of suds.

Since the rotation and vibration of the mold combine to reduce the timerequired to extract the excess water and air from the fill, it isapparent that the fluid concrete may be fed into the mold at a higherrate, thus reducing the molding time for a given article and increasingthe production capacity of the machine. To this end I prefer to feed asmall rapidly flowing stream of the mix instead of a slow moving streamof large section, as the small stream distributes the material moreevenly in the mold.

The extraction of excess water from the mix reduces the water content ofthe fill in the mold and produces a uniformly low-water-cement ratio,high-strength concrete for a wide variation in the water-cement ratio ofthe mix. This assures a uniform product, yet permits the use of a mixsufficiently fluid to flow readily into the mold. By vibrating the mold,the density of the fill at the center of the mold and the amount ofwater extracted are increased, both of which operate `to produce a moreuniform and stronger product in a shorter length of time than ispossible without vibrating the mold.

As the mold is filled and the diameter of the basin decreases, theoperator may increase the speed of rotation by increasing the speed ofmotor 19; This also increases they frequency of vibration. As thefrequency is increased the amplitude of the vibration may be decreasedby decreasing the raise of wheels 37 by controlling motor 40, thussecuring the most advantageous proportions for the basin throughout thelength of the mold.

As the paraboloidal basin rises the suds are carried upward in the moldand spilled from the top of tubular journal 66 over annular disc 75 fromwhich it is centrifuged into discharge basin 72. From there it flowsaway from the apparatus through spout 73, trough '74 and the connectedWaste pipe.

After the mold is filled, motor 40 may be energized to withdraw Wheels37 which are stopped in their lowest position by the operation of limitswitch 49. The rotation of the mold may then be continued at the same orat other speeds to further set the ll into the intricacies of the moldas the judgment of the operator may dictate.

The rotation of the mold is then stopped, trough 76 and appended funnel77 are removed and disc is unscrewed from tubular journal 66, thuspermitting the removal of bearing 69 and discharge basin 72. The moldmay then be removed frorn the spinning table by a crane or othersuitable means, after which tubular journal 66 is unbolted and removedfrom the mold and the concrete smoothed ofi level with the top ofthemold thus exposing conduit pipe 62. When the material has set, bolts57 are removed and the mold sections stripped from the finished article.

The adjustable rotation and vibration features of my invention areamenable to a wide variety of combinations during the molding process,which may be readily adapted to meet the requirements `for the rapid,economical and satisfactory molding of concrete articles having varioussizes, proportions and embellishments within the load capacity of themachine.

In general, the slower rotational speeds and greater amplitudes ofvibration are used in molding articles having relatively large lateralsectional dimensions, or in molding those sectional portions of anarticle having such dimensions; and the higher rotational speeds andsmaller amplitudes of vibration are used in molding articles havingrelatively small lateral dimensions, or in molding those portions of anarticle having such dimensions.

. For example, when molding short slender articles such as concreteposts, a relatively high constant speed and small amplitude of vibrationmay be used to maintain the top of the concrete ll in the form of basindesired, and at the same time centrifuge the outer portion and pack thecenter portion of the ll.

When molding relatively long. slender articles such as concrete polesand street lighting standards, I prefer to start filling the mold at arelatively slow speed and relatively large amplitude of vibration. Thelarger diameter at the lower end assures the proper centrifuging of theouter portion of the iill against the sides of the mold,

and the larger amplitude of vibration assures the packing of the fill atthe center of the mold While maintaining the'ascending top of the ll inthe form of a basin into which the suds are effectively squeezed. As themold is lled and the diameter decreases, the speed may be increased andthe amplitude of the vibrations decreased, care being taken to maintainthe basin in the top of the ll to receive the suds and nally spill itfrom the top of the mold. With the mold filled and the excess water andair removed in the suds, the mold may then be rotated to further packthe periphery of the ll into the small spaces of the mold, thus assuringa hard smooth surface and fully formed embellishments free from surfacedefects.

It will be apparent to those skilled in the art that various changes maybe made in the mech- Vco anism of the machine and in using theprinciples of the process without departing from the spirit and intentof the invention.

For example, the spinning table element may be eliminated and the baseof the mold adapted to engage the vertical driving shaft direct and tobe supported directly by the rollers. This requires precisionconstruction of the mold and precise positioning ofthe mold withreference to the actuating mechanism, Whereas in the form hereinillustrated and described, quite large inaccuracies in construction andalignment do not affect the satisfactoryoperation of the device.

` While I have shown two adjustable wheels 37, it is apparent that threeor morev such Wheels could be used. This might be desirable Where higherfrequency vibrations are required. Obviously non-rotating arcuateprojections could be substituted for wheels 37 as means for vibratingthe mold through the intermediacy ofthe rollers as they traverse thebase track. The number of support rollers, however, should be a multipleof the number of wheels or arcuate projections used.

Instead of mounting rollers 23 on a spider so spinning table 20 rests onthe periphery of the rollers, they could be axially mounted directly onthe base section of the mold or on the spinning table.` The speed ofrevolution around track 5 would then equal the, speed of rotation of themold, whereas it is half that speed with the arrangement shown.Furthermore the bearing sleeves of the rollers would have to be largerto carry the entire Weight of the mold,and only the resiliency of thelower halves of the rollers would be effective.

While I have specied the use of uid concrete, other concretiousmaterials may be used. In using the process, many variations may be madein the way the material is introduced, and in the use of the spinningand vibrating features in lling the mold to manufacture a given article.

Having thus described my invention what I claim as new and desire toprotect by Letters Patent, is:

1. In a centrifugal molding machine, the combination of an annular basetrack, a plurality of rollers adapted to traverse said track, arotatively driven upright mold supported by said rollers and arcuatemeans projecting above said base track for vibrating said mold throughthe intermediacy of said rollers.

2. In a centrifugal molding machine, the combination of an annular basetrack, a plurality of resilient rollers adapted to traverse said track,a rotatively driven upright mold supported by said rollers, andadjustable arcuate means projecting above said base track for vibratingsaid mold through the intermediacy of said rollers.

' 3: In a centrifugal molding machine, the combination of an annularbase track, a plurality of rollers Iadapted to traverse said track,revolvable spider means adapted to rotatively mount said rollersin xedspace relation around said track, an upright mold rotatably mounted onsaid rollers, and adjustable arcuate means projecting above said basetrack for vibrating said mold through the intermediacy of said rollers.

4. In a centrifugal molding machine, the combinationof an annular basetrack, a plurality of rollers adapted to traverse said track, a spinningtable revolvably supported on said rollers, a rotatively driven uprightshaft Apositioning said spinning table coaxial of said base track andproviding a sliding positive driving connection therewith, andadjustable arcuate means projecting above said base track for vibratingsaid spinning table through the intermediacy of said rollers.

5. In a centrifugal molding machine, the combination of an annular basetrack, a plurality of spaced rollers adapted to traverse said track, arevolvably driven spinning table supported by said rollers, a pluralityof apertures in said track in i the traverse of said rollers, eccentricsrotatively mounted below said apparatus, wheels revolvably mounted onsaid eccentrics and adapted to protrude through said apertures, wormgear means actuating said eccentrics thereby positioning said wheels tointercept said rollers and vibrate said spinning table, and worm pinionmeans actuating said worm gear means.

6. In a centrifugal molding machine, the combination of an annular basetrack, a plurality of spaced rollers adapted to traverse said track, arevolvably driven spinning table supported by said rollers, a pluralityof apertures in said track in the traverse of said rollers,eccentricsrotatively mounted below said apertures, wheels revolvably mounted onsaid eccentrics and adapted to protrude through said apertures, worm andgear means actuating said eccentrics whereby said wheels may beadjustably positioned to intercept said rollers and vibrate saidspinning table, power means actuating said Worm-and gear means, andmotion limit control means in rotative connection with said power meanswhereby s aid power means is stopped automaticallywhen said wheels,being raised, protrude their maximum distance above said base track, or,being. lowered, are withdrawn the maximum distance below said track.

7. The method of molding concrete articles, which consists of mounting amold in an upright position, pouring uid concrete into the upper endthereof, rotating said mold concurrent with said pouring to form a basinat the top of the ascending ll, and repeating the sequence of suddenlymoving said mold upwardly at a suitable rate gradually diminishing tozero, then sudden- 1y stopping the mold While moving downward at a rategradually increasing from said zero to pack the ll in said moldconcurrent with said pouring 'and said rotating.

8. In a centrifugal molding machine, the combination of an annular basetrack, a plurality of rollers adapted to traverse said track, arevolvably driven spinning table supported by said rollers, resilientmeans on said spinning table, an upright mold pivotally supported onsaid resilient means and positively driven by said spinning table, andarcuate means projecting above said track y for vibrating said moldthrough the intermediacy of said rollers, said spinning table and saidresilient means.

9. 'I'he method of manufacturing concrete articles, which consists ofmounting a mold in an upright position for axial rotation andlongitudinal vibration, concurrently pouring fluid concrete into themold and rotating and vibrating the same .to form a basin at the top ofthe fill, then varying the speed of said rotation to maintain a saidbasin while filling the different cross-sew tional space portions of themold.

10. The method of manufacturing concrete articles, which consists ofmounting a mold in an upright position for axial rotation andlongitudinal vibration, concurrently pouring fluid concrete into themold and rotating and vibrating the same to form a basin at the top ofthe ll, then varying the amplitude of said'vibration to maintain a sa-idbasin vwhile lling the different cross-sectional space portions of themold.

11. The method of manufacturing concrete ar-

